Nathan Wallwork discovered a buffer overflow in heartbeat, a subsystem for High-Availability Linux. A remote attacker could send a specially crafted UDP packet that overflows a buffer, leaving heartbeat to execute arbitrary code as root.
This problem has been fixed in version 0.4.9.0l-7.2 for the current stable distribution (woody) and version 0.4.9.2-1 for the unstable distribution (sid). The old stable distribution (potato) doesn't contain a heartbeat package.
We recommend that you upgrade your heartbeat package immediately if you run internet connected servers that are heartbeat-monitored.